Both XCOM: Enemy Unknown and Xenonauts are successors to the original X-COM series, but they offer players very different things when it comes to depth of gameplay.

For years there has been debate amongst video game fans about dumbing down, about streamlining games, cutting out features, making them easier to play and less challenging. Players lament the over-simplification of titles like Mass Effect 3, or Skyrim, but the debate is usually hypothetical because we only know about games that exist. There is no complicated version of Skyrim for comparison, ditto for the Mass Effect series. We can only conjecture on what might have happened had Bethesda used the Morrowind systems in Skyrim or if Bioware opted to perfect the cumbersome inventory systems of the original Mass Effect rather than ripping them out.

However, one instance where we can examine this subject outside of hypotheticals has come to light with the emergence of two X-COM games. XCOM: Enemy Unknown, produced by Firaxis, which shares the name and the legal ownership of the IP with the original series, and Xenonauts, an indie title produced by Goldhawk Interactive which is dubbed a re-imagining. Both games have appeared at roughly the same time after substantial development periods: Xenonauts has been in production since 2009, and work on the new XCOM: Enemy Unknown (now hyphen-free) began in 2008.X-COM games are a genre unto themselves, one that is clearly defined by the original title of the franchise - UFO: Enemy Unknown, created by British developer Julian Gollop, released in 1994.

In the X-COM games you are the head of an agency appointed to protect the Earth from alien invaders. The name of the agency, X-COM, is short for Extra-terrestrial Combat Unit, essentially a global group for stopping little green men from taking over the world. The games feature two main aspects: a campaign element where you build bases, research technology, manufacture equipment and marshal your forces, and a second element which is turn-based combat between squads of your troops and the aliens on the ground. That’s what an X-COM game should be and what the best ones always have been.

That said, the X-COM franchise has got about a bit, the name getting attached to all sorts of ill-fated projects over the years. There’s X-COM: Interceptor, which is a bad space fighter game; there’s X-COM: Enforcer, which is a bad third-person shooter; and recently there is The Bureau: XCOM Declassified, which is like some kind of developmental teleportation accident that we shall not speak of again.

There are also more legitimate offspring bearing the X-COM name. Terror From The Deep and Apocalypse are both straightforward sequels to Enemy Unknown. Terror From The Deep has you fighting against aliens on the seabed - the unforeseen consequence of shooting down enemy ships over the ocean - and Apocalypse has you defending a city from enemies appearing through inter-dimensional portals.

It is perhaps appropriate that the nautical-themed Terror From The Deep, only the second game, is where the series jumped the shark. X-COM is a franchise loved by many gamers, yet possesses arguably the worst ratio of classics to turkeys. Many franchises have done better yet few are so well-regarded by their fans. Make no mistake, UFO: Enemy Unknown was a masterpiece.

Games that have remained true to the X-COM genre have been rare until recently. Other games have attempted to use the campaign coupled to squad level combat idea, such as the UFO trilogy, but in opting for a post-apocalyptic setting the point of actually defending the Earth in that series was rendered somewhat moot.

XCOM: Enemy Unknown and Xenonauts are the first two legitimate heirs to the vacant Best X-Com Game crown in years, and both make a very good claim.

One key difference that should be acknowledged at the start between the two lies in the setting. XCOM takes place in the modern era, whereas Xenonauts begins in 1979 amid the cold war. This gives each game a somewhat different tone. XCOM is optimistic, warm and visually engaging, set in a modern world of satellites, globalisation and chunky heroic soldiers. Xenonauts has a more calculating and grown-up feel to it - you play in a world that was ready to destroy itself prior to the aliens turning up. The art style gives your troops a fragile, inoffensive appearance, more human than XCOM's armour-plated space marines despite the less impressive visuals.

XCOM does a lot of things right with its simplifications. There is a clearly-defined story and, if you want to chase it, you can. If you want to sit back in a holding pattern for a spell, you can do that too. You lead you team of soldiers, upgrading them as they get better at shooting aliens and as you gain access to better technology. Base building is clean, simple and intuitive, with the main limitations being money and power supply. Expanding your subterranean base complex gets more expensive the deeper you go. You pick where your base is at the start of the game to enable a bonus from the happy host continent. A clean-cut deputy, a wise old engineer and a ruthless scientist provide useful tips and comments as you go along, speculating on the alien threat and helping to provide atmosphere.

In the field you operate with a small team, starting with four soldiers and moving up to six as the game progresses. You fight the aliens on a selection of maps that do get familiar quickly, but manage to look pretty and blow up in entertaining ways. Explosions help to mitigate the repetitiveness a lot and despite the limitations of the game you can still improvise and adapt in combat within reason; cover and walls can be removed with sufficiently powerful weapons, new doors can be made, cars and fuel containers can be blown up to injure nearby enemies. The standard of presentation is very high and this makes the game more engaging to play, characters feel more convincing, the aliens feel more threatening, particularly when they are laying eggs in people, this is important stuff to the tone and feel of the game and XCOM does it well.

The small squad size brings major benefits to the ground combat part of the game. First, it brings pace - turns are short and snappy. Each soldier has two actions, which means any given turn will amount to you having to do at most twelve things. Secondly, it brings drama and tension, because every shot matters. When things start to go wrong things can get hairier quicker than a yeti in Movember. Make no mistake, for all its streamlining and presentational emphasis XCOM is not actually easy. It does get easier with experience of course, too easy in fact, but compared to most games it pulls few punches.

Xenonauts is not yet finished. Release date is later this year, maybe early next, and even in this state it is scary just how much more there is to it.
The campaign map, for example, allows you not just to build your base and choose where it goes as in XCOM, you can also choose to have more than one base. This harks back to the original game which also included multiple bases. You may need more than one base too, because the campaign game is vastly more sophisticated.

The first and most overt difference lies with the business of intercepting the alien spacecraft. XCOM does this by means of a mini-game. When you detect an alien ship the game pauses, allowing you to send up an interceptor, knock the alien out of the sky and send in your team to pick up any pieces. If the first interceptor fails you send another like minions in a Bruce Lee film. The aliens will sportingly only show up one at a time too and though some ships can shoot down interceptors you are normally equipped to deal with them before those ships make an appearance. Xenonauts,on the other hand, takes this part of the game to a higher level; alien ships appear in waves, with ships dropping into the atmosphere at many locations at once. What in XCOM is a rudimentary process becomes a contested front line in Xenonauts.

Air superiority is vital because merely having shot down an alien craft is no guarantee that you’ll be able to claim it. The first time that alien fighters shot down my squad transport en route to a crash site was a massive shock. That’s not the worst that they’ll do in Xenonauts either - if the enemy find one of your bases they will send troops to assault it. In XCOM the alienships will sometimes pick off your satellites but they won’t come round to your house to mess with your stuff.

On the ground Xenonauts is again more brutal than XCOM. XCOM has the aliens spawn in clumps, they do not exist on the map at the start of the game, rather you detect a group, when the group is detected the aliens appear, take cover, and the combat happens. This works well, it keeps the game rattling along, but it feels artificial and forced. Xenonauts has the aliens on the map at the start, usually murdering locals and finding rocks to hide behind. When it comes to the alien craft themselves, rather than spawning in when detected you can usually expect the crew of the ship to be dug in behind consoles, guns trained on the door, waiting to vaporise whichever poor rube you try to send through first. Larger ships and alien bases become a slaughter if approached carelessly.

The flexibility of Xenonauts allows for a variety of approaches. You can control much of the inventory of your soldiers and there are more options, from sniper rifles to breaching charges to armoured shields to knock out gas rockets and electric stun batons. Different size transports allow for more troops but even at the start you have a healthy eight. Despite this though there is still repetitiveness to the game. XCOM manages to mitigate this through its more directed narrative; Xenonauts,on the other hand, can feel like a bit of a slog at times.

Story progress with Xenonauts is less structured; there are no cut scenes to tell you where you are in the campaign and little sense that you are moving along a path. In some ways this helps to build the sense that your enemy is unknown, because you only learn about their patterns and plans from what you can observe yourself. Some of the threat of an unknown enemy is lost when a helpful scientist pops up every so often to tell you what they are up to. This lack of a defined story is liberating, you create your own story, but it can also be more demanding. The game does not hold your hand, not even for a moment. You need to deviseyour own strategy.

In terms of difficulty both games are challenging, yet in different ways. While XCOM can effectively kill you with one bad mission - particularly in an iron man game - Xenonauts offers all manner of ways for your campaign to go wrong but most of them are survivable. That first terror mission in XCOM is almost always something of a bastard, by contrast in Xenonauts the larger number of troops earlier in the game means that you typically won’t have any catastrophic failures.

For all the things you can do in Xenonauts is the game actually any better? Well, simply, yes. The acid test is a simple one, having played both games, which do I go back to? After Xenonauts the boundaries of XCOM loom large in every aspect of the game. It feels confining, and even lazy. Despite the reduced production values there is a sense of consistency and intelligence to Xenonauts that XCOM often loses, questions it doesn’t answer - like, why do all the interceptors have to fly one at a time? Why does the team have to consist of only four soldiers at the start? When XCOM feels most like a game, it loses the suspension of disbelief that, despite the dated visual style, Xenonauts clings to like a terrier.

There is nothing wrong with XCOM per se. Games reviews fixate on numbers, on scores, and ratings, and by any such measure it is impossible to say that XCOM is bad. It is fun and challenging and it kills time in an enjoyable way - would that all games could do that. As a successor to UFO: Enemy Unknown, however, it is a distant second to Xenonauts.